armnn: sync to 20.11 release am: a6543fa3a9

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/armnn/+/13555969

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I7ca840176ccbb1c2f8223d3ccc1b4ca78e1734b5